Massive iceberg breaks away from Antarctica’s Larsen ice shelf

A trillion-ton chunk of ice broke from Antarctica's Larsen C Ice Shelf this week, becoming one of the largest icebergs ever recorded

A trillion-ton chunk of ice broke from Antarctica’s Larsen C Ice Shelf some time between Monday, July 10 and July 12, according to the UK-based research group Project MIDAS.

NASA’s MODIS satellite detected the split, which resulted in a 5,800 square km (2,491 square mile)  iceberg that amounts to about 12 percent of the ice shelf’s mass.

The new iceberg is one of the largest ever recorded: Its total volume is more than twice that of Lake Erie, enough to cover all 50 U.S. states with 4.6 inches (117mm) of ice, or fill 463 million olympic-sized swimming pools, according to Heather Marie Zons of The Weather Channel.

The iceberg is much deeper than the Eiffel Tower is tall, averaging about 536m (1,760 feet) thick. Only a small part – about 61m (200 feet) – rises above sea level.

It weighs around a trillion tons and is the size of the U.S. state of Delaware (or one-quarter the size of Wales, half a Qatar, or seven New York Citys).

Project MIDAS said the iceberg is likely to be named A68.

The project’s scientists and researchers have monitored the ice chunk since 2014. The first crack appeared in the shelf in 2010.

“We have been anticipating this event for months, and have been surprised how long it took for the rift to break through the final few kilometres of ice. We will continue to monitor both the impact of this calving event on the Larsen C Ice Shelf, and the fate of this huge iceberg.

The iceberg is one of the largest recorded and its future progress is difficult to predict. It may remain in one piece but is more likely to break into fragments. Some of the ice may remain in the area for decades, while parts of the iceberg may drift north into warmer waters.”

Professor Adrian Luckman of Swansea University, Project MIDAS lead researcher

Sea level rise

The Larsen C shelf is the third to break from the Antarctic Peninsula Since 1995, USA Today reported. At 12 percent of the shelf’s weight, the publication noted that the loss of the new iceberg is not expected to significantly weaken the shelf.

Project MIDAS said the iceberg will have no immediate impact on sea level as it was already floating before breaking off the ice shelf.

When ice shelves lose mass, the glaciers that feed them have unrestricted flow directly into the ocean. This flow can push icebergs out to sea much more frequently. And with direct ocean access, glacial non-floating ice could dump into the oceans, having an eventual, albeit very modest, impact on sea levels.

The Larsen shelf may also be weaker after the cleave; MIDAS noted that a 2015 Swansea University publication said the rifts in the shelf prevent a significant risk to its stability.

“We find that the ice front is at risk of becoming unstable when the anticipated calving event occurs,” the report said of the break-away that occurred this week.

Changing landscape

Luckman reports that the Larsen C ice shelf is now at the smallest ever known size, and maps would need updating after the calving event.


Luckman said recent developments in satellite systems like Sentinel-1 and MODIS have improved researchers’ capabilities to monitor such events.

These upgraded systems will allow MIDAS Project scientists to obtain high resolution data more frequently and assess what remains of the Larsen shelf.

Larsen continues to show signs of thinning, due to both natural processes and global warming.

Dr. Martin O’Leary said the team will watch the ice shelf for further signs of instability: “Although this is a natural event, and we’re not aware of any link to human-induced climate change, this puts the ice shelf in a very vulnerable position. This is the furthest back that the ice front has been in recorded history.”


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